A restraining system of the aforementioned type is described, for example, in DE 103 04 943 B3. With the known restraining system, the associated seat belt retractor is part of an end fitting pretensioner in which the end of the seat belt to be fixed on the motor vehicle structure is fixed on the retractor shaft, so that this end of the seatbelt is wound up on the shaft upon actuation of the pretensioner drive and is tightened in this way. The locking of the shaft element with the seat belt retractor housing is undertaken in such a way that the locking element is arranged in the radial interior of the shaft element, which has a hollow configuration, and is pretensioned by means of a passage opening configured in the shaft element by spring action over the outer circumference of the shaft element until it engages in the associated gearing of the housing leg that supports the belt shaft. Consequently, the locking element is in a permanent locking with the seat belt retractor housing so that the end of the seat belt is correspondingly fixed and therewith fixedly mounted on the motor vehicle. When the pretensioner drive is activated, the locking element ratchets away through the gearing of the housing leg in the corresponding direction of the belt shaft, while in the event of a rotation of the belt shaft in the belt withdrawal direction after completing the pretensioning rotation, the immediate locking of the belt shaft takes place.
It is an object of the invention to increase the pretensioning force of a restraining system of the type described above.
This object, including the advantageous embodiments and further developments of the invention, is attained with the features of the present invention described herein.